Deactivating existing bearer/context for emergency bearer establishment

ABSTRACT

A method, user equipment and non-transitory computer readable memory for establishing an emergency service using a wireless network includes unilaterally deactivating, at the user equipment when the user equipment needs to establish an emergency service, at least one active context with the wireless network without deactivating at least one other active context. Thereafter directing to the wireless network, a request to establish the emergency service that identifies the emergency service and one or more contexts that remain active after the unilateral deactivation of the at least one active context by the user equipment, synchronizing, in response to and based on the request, current context status information of the user equipment with the wireless network, and then establishing the emergency service using the wireless network with which the active context was deactivated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of U.S. patent application Ser. No. 13/307,386,filed Nov. 30, 2011, which in turn claims the benefit under 35 U.S.C.§119 of GB 1120537.4, filed Nov. 29, 2011, the entire disclosure of eachof which is incorporated herein by reference.

TECHNICAL FIELD

The exemplary and non-limiting embodiments of this invention relategenerally to wireless communication systems, methods, devices andcomputer programs, and more specifically relate to establishing wirelessemergency services particularly when too many resources are in use fornon-emergency purposes.

BACKGROUND INFORMATION

The following abbreviations that may be found in the specificationand/or the drawing figures are defined as follows:

3GPP third generation partnership project

DL downlink

EPS evolved packet system

EUTRAN evolved UTRAN

GPRS general packet radio service

IMS Internet protocol multimedia subsystem

PDN packet data network

PDP packet data protocol

PS packet switched (domain)

QCI quality class indicator

RAT radio access technology

RR radio resource

RRC radio resource control

UE user equipment

UL uplink

UTRAN universal terrestrial radio access network

VoIP voice over Internet protocol

IMS services such as IMS VoIP use a PS domain bearer for PS connectivityin the serving network. IMS voice emergency sessions also use PS domainbearers (see 3GPP TS 23.060 v10.5.0 and 3GPP TS 23.401 v10.5.0). The PSdomain provides the bearer as PDN connections that consist of one ormore contexts as detailed at 3GPP TS 23.401 v10.5.0. “Contexts” in theGPRS radio access technology refers to PDP contexts, and in the EPSradio access technology refers to EPS bearer contexts. 3GPP TS 24.008v10.4.0 and 3GPP TS 24.301 v10.4.0 detail that the UE may support amaximum of 11 simultaneous contexts. This is the maximum allowed by the3GPP system and different UE models and manufacturers may support lessthan the maximum 11 contexts. For example, EUTRAN category 3 devicesrequire only eight contexts. Certain other implementation reasons mayleave a UE with the capacity to support only a maximum of six contexts,though in practice some widely deployed UEs support up to five contexts,many networks support only three and it appears that at least one mobiledevice operating system is limited to supporting only one context forits host UE.

In practice, it is possible that any given UE has PS domain bearersestablished for other purposes at the time the UE sees the need toestablish PS emergency bearer services. In normal operation an IMS VoIPcapable UE may have several contexts established; IMS VoIP itselfreserves one context for signaling purposes that is used for registeringto the IMS and also to establish normal (non-emergency) sessions. Thenthe UE may also have an additional PDN connection.

The PDN need not support IP dual stack (IPv4 and IPv6), in which casethe PDN supporting both IP versions instructs the UE to establishseparate PDN connections; one for IPv4 traffic and one for IPv6 traffic(see 3GPP TS 24.008 v10.4.0 and 3GPP TS 24.301 v10.4.0; thesespecifications use the term should instead of may for the network‘instructing’ summarized above). This network configuration can doublethe number of active contexts that the UE must handle in parallel.

Regardless of the number of simultaneous contexts supported by the UEand the capabilities of the UE and the network to support (or not) dualstack bearers and different IP versions, it is possible that at a giventime for a given UE the maximum number of contexts have already beenactivated for other purposes at the time of emergency VoIP voice callestablishment. The UE will detect that it does not have enough resourcesto proceed with PS emergency bearer establishment due to too many activecontexts.

A typical network configuration would still allow emergency access viaso called Access Class 10 for a UE whose access for other services isbarred (see 3GPP TS 22.011 v11.1.0 clause 4.4). Access Class 10 isbroadcast in system information and informs UEs in the cell whether theyare allowed to initiate an emergency call regardless of their accessclass barring status, so this allows the UE to establish an emergencycall. Context deactivation is a normal priority procedure and subject tobarring, so if the UE already has got its maximum number of activecontexts, it is not allowed to deactivate PDP contexts in GPRS or todisconnect the PDN in EPS in order to relieve the necessary resourcesfor the subsequent emergency call that would be allowed in thissituation. But IMS emergency services are not yet deployed in realnetworks and devices, and so these problems related to establishing themhave not yet been encountered in practice. Below is a review of relevantprocedures for emergency services in GPRS and EPS networks.

There is an option already specified for a UE to use a PS attachprocedure for emergency purposes, but this is restricted to a strictlylimited service case when the UE cannot attach to the network for anyother than emergency services (see 3GPP TS 24.008 v10.4.0 and 3GPP24.301 v10.4.0). Those same specifications detail a service requestprocedure for a UE to initiate new services that has alreadysuccessfully attached to the network. The GPRS service request containsPDP context status for the purpose of synchronizing the PDP contextstatus between the UE and the network, if for some reasonre-synchronizing is necessary.

If the UE has run out of EPS bearer contexts or GPRS PDP contexts, thenit is allowed (per 3GPP TS 24.008 v10.4.0 and 3GPP 24.301 v10.4.0) torelieve either some or all of those resources by means of a UE-initiatedEPS PDN disconnect procedure or a PDP context deactivation in GPRS andthen establish the connectivity that is required for a PS emergencycall. There are two shortfalls with this prior art approach: a) itimposes a long delay to establish an emergency call, and b) it may notbe possible if the UE's Access Class is barred per clause 4 of 3GPP TS22.011 v11.1.0.

So in current practice emergency calls can override several obstaclesthat would otherwise deny the UEs right for uplink access, such as ifthe UE is in limited service and is not able to attach for normalservice or having a network assigned back-off timer running. But if theUEs access to the network is barred, the UE-initiated deactivation ofPDP contexts in GPRS and the UE-requested PDN disconnect procedure inEPS are forbidden. The UE would be allowed to establish an emergencycall, but cannot do so since the procedures to relieve the resourcesthat are essentially required for setting up the emergency call arenormal priority procedures with no possibility to indicate “emergency”use. See 3GPP TS 44.018 clause 3.3.1.1.1; 3GPP TS 36.331 clause 5.3.3and 3GPP TS 25.331 clause 8.1.8.

What is needed in the art is a way to assure a UE which needs toestablish emergency services may do so under any conditions so long asthe UE has sufficient signal strength with the network, and withoutundue delay given the emergency nature of the call.

SUMMARY

In a first exemplary embodiment of the invention there is a method forestablishing an emergency service for a user equipment using a wirelessnetwork. The method includes unilaterally deactivating, at the userequipment when the user equipment needs to establish an emergencyservice, at least one active context with the wireless network withoutdeactivating at least one other active context; thereafter directing tothe wireless network, a request to establish the emergency service andthat identifies the emergency service and one or more contexts thatremain active after the unilateral deactivation of the at least oneactive context by the user equipment; synchronizing, in response to andbased on the request, current context status information of the userequipment with the wireless network, and then establishing the emergencyservice using the wireless network with which the active context wasdeactivated.

In a second exemplary embodiment of the invention there is a portabletelecommunications user equipment, which includes a processing systemincluding at least one processor and at least one memory storing acomputer program. The at least one memory with the computer program isconfigured with the at least one processor to cause the user equipmentto at least: unilaterally deactivate at least one active context with awireless network without deactivating at least one other active contextwhen the user equipment needs to establish an emergency service;thereafter direct to the wireless network, a request to establish theemergency service and that identifies the emergency service and one ormore contexts that remain active after the unilateral deactivation ofthe at least one active context by the user equipment, such that inresponse to and based thereon, current context status information of theuser equipment is synchronized with the wireless network, and thenestablish the emergency service using the wireless network with whichthe active context was deactivated.

In a third exemplary embodiment of the invention there is anon-transitory computer readable memory tangibly storing a computerprogram executable by at least one processor. The computer programincludes code to be executed on a processing system of a user equipment.The code unilaterally deactivates, when the user equipment needs toestablish an emergency service, at least one active context with thewireless network without deactivating at least one other active context.Thereafter the code directs to the wireless network, a request toestablish the emergency service and that identifies the emergencyservice and one or more contexts that remain active after the unilateraldeactivation of the at least one active context by the user equipment,synchronizes, in response to and based on the request, current contextstatus information of the user equipment with the wireless network, andthen establishes the emergency service using the wireless network withwhich the active context was deactivated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a signaling diagram illustrating a local detach followed by anemergency attach for UE that is already attached to a cell needing toestablish emergency services, according to an exemplary embodiment ofthese teachings.

FIG. 2 is a signaling diagram illustrating a UE's local deactivation ofcontexts followed by its SERVICE REQUEST indicating context status forestablishing emergency services according to an exemplary embodiment ofthese teachings.

FIG. 3 is a signaling diagram illustrating a UE's deactivation ofcontexts followed by establishment of emergency contexts according to anexemplary embodiment of these teachings.

FIG. 4 is a logic flow diagram that illustrates from the perspective ofthe UE the operation of a method, and a result of execution of computerprogram instructions embodied on a computer readable memory, inaccordance with exemplary embodiments of these teachings.

FIG. 5 is a simplified block diagram showing the UE and a network accessnode, and are exemplary electronic devices suitable for use inpracticing the exemplary embodiments of this invention.

DETAILED DESCRIPTION

In general, a UE which has too many active contexts to add another foran emergency call will need to prioritize its emergency request abovethe other services and make the necessary resources available, even ifit means deactivating some other connections that are used for lowerpriority services. The network needs to be informed about the UE'scontext status, which contexts are kept and which one is deactivated, torelieve resources for the PS emergency call. This problem isparticularly difficult for EPS technology where there is no means forthe UE to indicate the current EPS bearer context status to the network.In GPRS it is less difficult because the UE uses GPRS mobilitymanagement protocol service requests that contain a PDP statusinformation element, though in GPRS the UE still needs to have somemeans for deactivating PDP contexts to ensure resources are availablefor an IMS emergency session.

One aspect of these teachings is how the UE selects which ongoing(non-emergency) services to abandon in favor of establishing a higherpriority emergency call, as well as the means to indicate this choice tothe network with minimum signaling overhead. In order to optimize thesignaling to speed up the emergency call establishment, certainembodiments of these teachings detailed below utilize implicitsignaling; this avoids extra delays caused by session managementprotocol deactivation signaling that would have to be executed prior towhen the UE first actually requests PS emergency bearer services.

This situation, in which the UE needing an emergency service for whichit has no excess PDP or EPS contexts, is resolved by the exampleimplementations shown at FIGS. 1-2. Namely, the UE selects one or morecontexts that are locally deactivated, and uses enhanced signaling torequest the emergency services of the wireless network. One suchenhanced signaling is to use an Extended Service Request procedureinstead of the conventional Service Request procedure.

But as noted in the background section above, there is another problemin prior art emergency call setup in that there is a process for a UEwhich is camped in a cell but not attached to the network to establishan emergency call, but no process to do so if the UE is already attachedto the network, even if it's not using all its contexts. When the UE isattached the core network is aware of the UE's presence since the corenetwork authorizes that attachment, but if the UE is only camping on thecell the core network is not aware of its presence. The procedure the UEmust use in that latter ‘attached’ case is to request a normalconnection, which the UE is not able to specify is for an emergencyservice. If there are insufficient resources in the cell the UE'srequest may easily be denied since the network will not know thatrequest is for preparing a subsequent emergency request.

This situation is resolved by the example implementation shown at FIG.1, an emergency attach procedure. While the emergency attach procedureis currently specified to be used by a UE only when attempting PSemergency access while camped on a cell not providing normal services,FIG. 1 shows an adaptation which resolves the problems above in case theUE is attached to the network rather than only camped in a cell, namelya local detach followed by an emergency attach.

FIG. 1 is a signaling diagram illustrating this solution. For each ofFIGS. 1-3, there is illustrated signaling between the UE 20, a packetswitched core network 30 and an IMS core network 40. From the UE'sperspective the signaling is between itself and a network access nodesuch as a NodeB or an eNB as shown at FIG. 5; that access node thenrelays the relevant messages (or content thereof) to the PS core network30 which as shown further relays the relevant information to and fromthe IMS network 40.

FIG. 1 begins with the UE 20 having an active PS connection 102 with thePS core network 30. This means the UE is attached to the network, and asnoted above this precludes the UE 20 from using the conventionalemergency attach procedure which is reserved only for UEs which are onlycamped in the cell (for example, if the UE is not allowed normal accessto this cell but is allowed to access it for emergency purposes only).At 104 the UE detects a need to establish an emergency data session. Forexample, the UE may be a vehicle mounted device using the PS domainconnection for real-time navigation when an auto accident occurs and theUE knows, from a particular user input (or series of inputs) or fromautomatic connection to crash/airbag deployment sensors, to establish anemergency connection. At block 106 the UE unilaterally locally detachesfrom the connection of 102 and the UE sends an emergency attach messageat 108. In an embodiment there is no additional user input needed forthe local detach 106 operation; initiating an emergency call as noted inthe example auto accident scenario above is sufficient to trigger boththe local detach 106 and the emergency attach 108 protocols.

Initiating the emergency attach 108 with the local detach 106 allows theUE to start ‘from clear’ to proceed with the emergency attach 108, thatis, the UE starts the emergency attach 108 without an existingattachment 102 to the network. This establishes a mobility managementconnection for session management protocol and clears the reservedresources which were reserved for the previous attach 102, freeing thoseresources for establishing the emergency session.

The remainder of FIG. 1 is similar also at FIGS. 2-3, with exceptionsnoted for the IMS registration 112, 212 and 312. Specifically, followingthe emergency attach message 108 the PS core network 30 and the UE 20exchange signaling to establish emergency PDN services 110, such as forexample to establish a single PDP (GPRS) or EPS context for IMSsignaling. Once established the session is registered to the IMS corenetwork 40 and the emergency session is established at 112, and finallythe PS core network 30 can establish for the UE 20 a media bearer 114for which the context established at 110 will be active, a VoIP contexton the emergency session in this example. Since the UE detaches at block106 of FIG. 1, the registration to the IMS at message exchange 112 ofFIG. 1 is always required after the PDN is established at messageexchange 110. The FIG. 1 embodiment is quite useful for the case thereis a resource shortage in the network. This is because if the UE were tosimply request another bearer by conventional procedures it could notindicate to the network that the requested bearer was for emergencyservices.

The embodiment of FIG. 2 utilizes an extended service request toestablish emergency signaling and to indicate the UE's context status,to inform the network of those contexts which the UE 20 has locallydeactivated. In this embodiment, before signaling anything to thenetwork 30 the UE 20 has detected that is has too many active contextsin its active PS domain communications 202 to co-exist with an IMSemergency session which the UE 20 would like to establish afterdetecting a need for it at 204.

In an embodiment of these teachings there is an algorithm by which theUE 20 methodically chooses which one or more PDP or EPS contexts tolocally deactivate. In order to assure that the network can provide aVoIP bearer that ensures a sufficient amount of resources for theemergency call (for example, aggregate downlink and uplink bit rates forthe UE 20), the UE 20 will deactivate some or all bearer resources thatprovide guaranteed bit rates. If these alone do not free up enoughresources the next contexts to be deactivated are the remainingnon-guaranteed bit rate bearers. More particularly, in one specificembodiment the selection algorithm goes through the established bearersin their priority order, QCI 4-QCI 1, QCI 9-QC15. QCI is a scalarrepresenting quality of service class identifier that is used as areference to access node-specific parameters that control bearer levelpacket forwarding treatment (e.g. scheduling weights, admissionthresholds, queue management thresholds, link layer protocolconfiguration, etc.). The UE may also apply activity monitoring indetermination of PDP or EPS contexts to be deactivated; those withlittle activity are considered a lower priority, and the algorithmconsiders them sooner for deactivation, than bearers having a higherlevel of traffic/activity.

Once the UE 20 has locally deactivated one or more of its PDP or EPScontexts the UE prepares an extended service request 208 to inform thenetwork which contexts remain active (for example, a bitmap). The use ofthe extended service request is currently used for circuit-switched fallback (see 3GPP TS 24.301 v10.4.0, which specifies that circuit-switchedservices can be used in case packet-switched services cannot) andcontains an information element to synchronize the EPS context statusbetween the UE and the network only for that circuit switched fall back.The normal service request enables no such synchronization. Typically,the circuit-switched fall back is used for speech orshort-message-service/text messaging scenarios. In the FIG. 2 embodimentthere is a new service type (for example, added to subclause 9.9.3.27 of3GPP TS 24.301 v10.4.0) allocated for emergency session use. This newservice type enables the extended service request to be used foremergency signaling connection establishment. In order that thisembodiment may be easily backward compatible with legacy signaling thereis a value reserved with the default handling of the service type‘packet services via S1’ for indicating emergency signaling connectionestablishment. This signaling connection is then used for activating acontext for IMS emergency session initialization. In the referencespecification version, the extended service request PDU already containsan EPS bearer context status information element that the UE 20 can usein the FIG. 2 embodiment to indicate to the network 30 all the remainingcontexts that the UE 20 has not deactivated and which the UE 20 stillconsiders active prior to the emergency bearer establishment. That is,the UE 20 locally deactivates one or more PDP or EPS contexts at 206 andthe status information element in the extended service request 208 isused for synchronizing its current context status information with thenetwork 30.

The extended service request 208 establishes the RR connection at 210with the access stratum/access node of the network and indicates‘emergency’ as the establishment cause. This cause is delivered by theradio access network (GPRS or EPS) to the packet switched core network30 in S1 connection establishment signaling. Since the emergency PDNservices establishment signaling 210 identifies ‘emergency’ as theestablishment cause, in a particular embodiment of these teachings thereis no similar indicator of ‘emergency’ in the extended service request208 (for example, such an emergency indication is absent from the‘service type’ field of that message 208). In other embodiments the‘service type’ field of message 208 indicates emergency service inaddition to the emergency establishment cause in message 210.

For the remainder of FIG. 2, the PS core network 30 and the UE 20exchange signaling to establish emergency PDN services 210, such as forexample to establish a single PDP (GPRS) or EPS context for IMSsignaling. Once established the session is registered to the IMS corenetwork 40 and the emergency session is established at 212, and finallythe PS core network 30 can establish for the UE 20 a media bearer 214for which the PDP or EPS context established at 210 will be active, aVoIP context on the emergency session in this example.

A new registration to the IMS services at exchange 212 may or may not beneeded. IMS registration is made with dedicated signaling on a defaultbearer to a specific PDN. For FIG. 1 any previous registration from theUE being attached at 102 was lost from its detach at 106. In FIG. 2there is no detach, only a PDP or EPS context deactivation at 206. Sothe UE may in some cases remain registered to its home public landmobile network which can provide the IMS services, in which case thereis no additional IMS registration needed at exchange 212. The IMSregistration in the exchange of 212 is conditional on whether thenetwork requires a new PDN connection for the UE 20 to a local accesspoint that will provide local IMS emergency service (the networkindicates whether it supports this ‘emergency bearer services’ featurethrough evolved mobility management EMM and GPRS mobility management GMMsignaling). 3GPP TS 23.167 clause 7.2 lists a set of conditions whichmust be met before a UE can initiate an emergency IMS registration(either not registered or roaming; has sufficient credentials toauthenticate; and is able to detect an emergency session) and in anexemplary embodiment of these teachings those also give the conditionsunder which the UE registers to IMS emergency services at messageexchange 212.

While the embodiments of FIGS. 1-2 are based on local deactivation ofPDP or EPS contexts without the UE specifically signaling thatdeactivation to the network, the FIG. 3 embodiment details explicitsignaling by the UE of the deactivated PDP or PDN context(s) followingthe UE's service request for an emergency call. As with FIG. 2, at FIG.3 before signaling anything to the network 30 the UE 20 has detectedthat is has too many active PDP (GPRS) or EPS contexts in its active PSdomain communications 302 to co-exist with an IMS emergency sessionwhich the UE 20 would like to establish after detecting a need for it at304. In this embodiment also the UE 20 may apply a prioritizationalgorithm as detailed above for the FIG. 2 embodiment so as to determinewhich of its active context(s) is/are to be deactivated and which are tobe retained. The UE 20 must be able to signal at 308 a sufficient numberof contexts which are deactivated to make space for the subsequentemergency connectivity, which means the conventional requirement for theUE to analyze whether or not it is barred need to be changed.

In conventional practice before a PDN disconnect the UE needs toinitiate a service request procedure but 3GPP TS 24.301 v10.4.0 at AnnexD.1 allows the UE to indicate the RRC establishment cause as “emergencycalls” only if the SERVICE REQUEST message is sent for the followingreasons:

-   -   If a SERVICE REQUEST is to request user plane radio resources        for emergency bearer services, the RRC establishment cause shall        be set to Emergency call. (See Note 1)    -   If a SERVICE REQUEST is triggered by a PDN CONNECTIVITY REQUEST        that has request type set to “emergency”, the RRC establishment        cause shall be set to Emergency call. (See Note 1)

For the second item above, the conventional procedures provide that theSERVICE REQUEST for PDN DISCONNECT REQUEST shall be sent using“originating calls” RRC establishment cause, which for the case of FIG.3 does not give the network any indication of the real reason for thedisconnect which is to relieve resources for a subsequent emergencyrequest that will follow as soon as the required resources areavailable. In a normal case this only reduces the priority of theprocedure that is preparing ground for emergency request, but if the UEsAccess Class is barred, this drawback blocks the PS emergency callcompletely as no PDN connectivity resources can be freed for theemergency request.

Therefore, in this embodiment the UE 20 will send the SERVICE REQUEST306 which has the RRC establishment cause identified as “emergency call”prior to the PDN DISCONNECT REQUEST 308. To implement this in GPRS andEPS the relevant specifications will need to be adapted to allow thisorder of the messages.

It is also advantageous that the PDP context deactivation (GPRS) and PDNdisconnect (EPS) procedures (both message 308 of FIG. 3) should beinitiated with indicated RRC establishment cause “emergency calls” or byoverriding the Access Class Barring evaluation for context deactivationthat is required for subsequent outgoing emergency connectivity request.

Following the UE's service request indicating emergency session 306 andthe indication of which contexts the UE deactivated 308 theestablishment of a PS emergency call proceeds normally and as detailedfor FIGS. 1-2. Specifically, the PS core network 30 and the UE 20exchange signaling to establish emergency PDN services 310, such as forexample to establish a single PDP (GPRS) or EPS context for IMSsignaling. Once established the session is registered to the IMS corenetwork 40 and the emergency session is established at 312, and finallythe PS core network 30 can establish for the UE 20 a media bearer 314for which the context established at 310 will be active, a VoIP contexton the emergency session in this example. The IMS registration at 312 isconditional, using the same conditions described at FIG. 2 for messageexchange 212.

Exemplary embodiments of these teachings provide the following technicaleffects. The solution detailed with respect to FIG. 1 has the advantageof being already a specified procedure, so it is simple to implement asit re-uses a limited service state procedure (camped in the cell only)in the normal service state (attached to the network). It is also anadvantage that no additional session management signaling is required.The drawback that all data communications are removed (meaning the UEmay need to re-establish connections again after the emergencyconnection is no longer needed) is seen to be minor since the emergencymay be quite severe against possibly trivial non-emergency datasessions.

A technical effect arising from the FIG. 2 embodiment is that allresources that are not absolutely required to process the PS emergencycall are preserved. The FIG. 2 embodiment aligns simply with GPRS and sowould be quite simple to adopt in that RAT since no additional sessionmanagement signaling is required. While this embodiment may change theconventional procedure to cover a wider range of services, since thisrelates to emergency services the change is seen to be worthwhile. Thereare two main distinctions over the conventional procedures with FIG. 2;namely there is a local deactivation of PDP context (GPRS) or local PDNdisconnection (EPS) without explicit signaling, and the PDP context/PDNconnection synchronization mechanism is added to the EXTENDED SERVICEREQUEST which is conventionally used for a different purpose and cannotindicate active or deactivated contexts.

It is also possible for another embodiment to enhance the emergencyattach of FIG. 1 by adding an EPS context status. This improves the FIG.1 embodiment at the cost of adding that EPS context status informationelement to the ATTACH REQUEST message. This may or may not be the mostefficient signaling since that information element would remain but beunnecessary for non-emergency attach instances.

The FIG. 3 embodiment provides the technical effect of clearing out thePDP context of PDN connectivity resources in preparation for asubsequent emergency call in the SERVICE REQUEST message, but suchexplicit signaling is less elegant than the FIG. 2 embodiment. The RRCestablishment cause “emergency call” can only be applied from theemergency call related signaling and the SERVICE REQUEST would besignaled using normal priority, but this is the way around the UE'saccess class being barred and the prior art emergency call establishmentnot even getting through. This also is easy to adopt since it followsexisting procedures fairly closely, with the change that the UE's use ofthe “emergency call” as its RRC establishment cause or its overriding ofits access class being barred.

Now are detailed with reference to FIG. 4 further particular exemplaryembodiments from the perspective of the UE 20. FIG. 4 may be performedby the whole UE 20 shown at FIG. 4, or by one or several componentsthereof such as a modem. At block 402, in response to determining that aUE having an active connection with a wireless network needs toestablish an emergency service, the UE unilaterally deactivates anactive session or context with the wireless network. For the case shownat FIG. 1 the UE may begin with an active radio connection. For thecases shown at FIGS. 2-3 the UE may be in idle mode and begin with oneor more active logical connections but no active radio connection, whichhave been released and require establishment before any signaling withthe network. These two scenarios are evident from the ‘active session orcontext’ which in block 402 is deactivated. Thereafter at block 404 theUE sends to the wireless network signaling to establish the emergencyservice, in which the signaling specifically identifies the service asan emergency service.

Further portions of FIG. 4 represent various of the specific butnon-limiting embodiments detailed above. Block 406 relates to the FIG. 1embodiment and specifies that the unilateral deactivating of block 402is the UE locally detaching from an active packet domain communicationwith the wireless network; and that the signaling of block 404 is anemergency attach which is established following the local detachingwhich clears resources used for the active packet domain communication.

Block 408 relates to the FIG. 2 embodiment, in which the unilateraldeactivating of block 402 is at block 408 the UE deactivating one ormore (PDP or EPS) contexts; and the signaling of block 404 is anextended service request which identifies one or more contexts whichremains active after the deactivating.

Block 410 relates to the FIG. 3 embodiment, in which the unilateraldeactivating of block 402 is at block 410 the UE deactivating one ormore contexts; and the signaling of block 404 is specifically at block410 a deactivation message explicitly indicating which one or morecontexts are deactivated. Block 412 has further implementation detailsof this embodiment; the signaling to establish the emergency servicecomprises a SERVICE REQUEST and the deactivation message comprises oneof a PDN CONTEXT DEACTIVATION or a PDN DISCONNECT REQUEST, and thedeactivation message has a cause indicator explicitly identifying theservice as an emergency service.

FIG. 4 is a logic flow diagram which may be considered to illustrate theoperation of a method, and a result of execution of a computer programstored in a computer readable memory, and a specific manner in whichcomponents of an electronic device such as the UE are configured tocause that electronic device to operate. The various blocks shown inFIG. 4 may also be considered as a plurality of coupled logic circuitelements constructed to carry out the associated function(s), orspecific result of strings of computer program code stored in a memory.

Such blocks and the functions they represent are non-limiting examples,and may be practiced in various components such as integrated circuitchips and modules, and that the exemplary embodiments of this inventionmay be realized in an apparatus that is embodied as an integratedcircuit. The integrated circuit, or circuits, may comprise circuitry (aswell as possibly firmware) for embodying at least one or more of a dataprocessor or data processors, a digital signal processor or processors,baseband circuitry and radio frequency circuitry that are configurableso as to operate in accordance with the exemplary embodiments of thisinvention.

Reference is now made to FIG. 5 for illustrating a simplified blockdiagram of various electronic devices and apparatus that are suitablefor use in practicing the exemplary embodiments of this invention. InFIG. 5 there is a UE 20 in the GPRS or EPS system operating under anetwork access node 22 (such as a Node B or an eNodeB) via wireless link21. The radio access network (GPRS or EPS) which includes the accessnode includes a higher network node (radio network controller RNC ormobility management entity MME) 24 which provides connectivity withfurther networks such as for example the PS and IMS core networks 30, 40shown at FIGS. 1-3. There is also a data/control path 23 coupling theaccess node 22 with the higher network node 22.

The UE 20 includes processing means such as at least one data processor(DP) 20A, storing means such as at least one computer-readable memory(MEM) 20B storing at least one computer program (PROG) 20C,communicating means such as a transmitter TX 20D and a receiver RX 20Efor bidirectional wireless communications with the eNB 22 and with thesecond device 26 via one or more antennas 20F. While only onetransmitter and receiver are shown it is understood there may be morethan one. Also stored in the MEM 20B at reference number 20G are theemergency bearer establishment signaling procedures according to theseteachings as detailed above, and the rules/algorithm for prioritizingcontexts as also detailed above.

The access node 22 also includes processing means such as at least onedata processor (DP) 22A, storing means such as at least onecomputer-readable memory (MEM) 22B storing at least one computer program(PROG) 22C, and communicating means such as a transmitter TX 22D and areceiver RX 22E for bidirectional wireless communications with the UE 20via one or more antennas 22F. The emergency bearer establishmentsignaling procedures according to these teachings as detailed above arestored in the memory 22B of the access node 22 at unit 22G.

The higher network node 24 has functionally similar capabilities forprocessor 24A, memory 24B and programs 24C. While not particularlyillustrated for the UE 20 or access node 22, those apparatus are alsoassumed to include as part of their wireless communicating means a modemsimilar to that shown for the higher network node at 24H, and which maybe inbuilt on an RF front end chip within those devices 20, 22 and whichalso carries the TX 20D/22D and the RX 20E/22E.

At least one of the PROGs 20C/22C in the UE 20 and in the network accessnode 22 is assumed to include program instructions that, when executedby the associated DP 20A/22A, enable the device to operate in accordancewith the exemplary embodiments of this invention, as was discussed abovein detail. In these regards the exemplary embodiments of this inventionmay be implemented at least in part by computer software stored on theMEM 20B, 22B which is executable by the DP 20A/22A of the devices 20,22; or by hardware, or by a combination of tangibly stored software andhardware (and tangibly stored firmware). Electronic devices implementingthese aspects of the invention need not be the entire apparatus 20, 22,as shown, but exemplary embodiments may be implemented by one or morecomponents of same such as the above described tangibly stored software,hardware, firmware and DP, or a system on a chip SOC or an applicationspecific integrated circuit ASIC or a digital signal processor DSP.

In general, the various embodiments of the UE 20 can include, but arenot limited to: data cards, USB dongles, cellular telephones; personalportable digital devices having wireless communication capabilitiesincluding but not limited to laptop/palmtop/tablet computers, digitalcameras and music devices, Internet appliances, remotely operatedrobotic devices or machine-to-machine communication devices.

Various embodiments of the computer readable MEMs 20B/22B include anydata storage technology type which is suitable to the local technicalenvironment, including but not limited to semiconductor based memorydevices, magnetic memory devices and systems, optical memory devices andsystems, fixed memory, removable memory, disc memory, flash memory,DRAM, SRAM, EEPROM and the like. Various embodiments of the DPs 20A/22Ainclude but are not limited to general purpose computers, specialpurpose computers, microprocessors, digital signal processors (DSPs) andmulti-core processors.

Various modifications and adaptations to the foregoing exemplaryembodiments of this invention may become apparent to those skilled inthe relevant arts in view of the foregoing description. While theexemplary embodiments have been described above in the context of theGPRS and EPS systems, it should be appreciated that the exemplaryembodiments of this invention are not limited for use with only this oneparticular type of wireless communication system, and that they may beused to advantage in other wireless communication systems such as forexample UTRAN and others in which UEs may need to set up emergencyservices while already attached to the network.

Some of the various features of the above non-limiting embodiments maybe used to advantage without the corresponding use of other describedfeatures. The foregoing description should therefore be considered asmerely illustrative of the principles, teachings and exemplaryembodiments of this invention, and not in limitation thereof.

1-24. (canceled)
 25. A method, comprising: deactivating a first activecontext with a wireless network, by a user equipment, while maintaininga second context as active, responsive to a request to establish anemergency service; and transmitting a request to establish the emergencyservice to the wireless network, by the user equipment, the requestidentifying the emergency service and the active second context.
 26. Themethod of claim 25, further comprising establishing the emergencyservice, by the user equipment, using the wireless network with whichthe first context was deactivated.
 27. The method of claim 25, whereindeactivating the first active context is performed unilaterally.
 28. Themethod of claim 25, further comprising transmitting an emergency attachrequest to the wireless network, by the user equipment, responsive tothe local deactivation clearing resources used for active packet domaincommunication.
 29. The method of claim 25, wherein deactivating thefirst active context further comprises transmitting a deactivationmessage to the wireless network explicitly indicating the first contextas a deactivated context.
 30. The method of claim 29, whereintransmitting the deactivation message to the wireless network isperformed subsequent to transmission of the request to the wirelessnetwork to establish the emergency service.
 31. The method of claim 29,wherein the request to establish the emergency service transmitted tothe wireless network comprises a SERVICE REQUEST and the deactivationmessage transmitted to the wireless network comprises one of a PDNCONTEXT DEACTIVATION or a PDN DISCONNECT REQUEST including a causeindicator explicitly identifying the service as an emergency service.32. The method of claim 31, wherein the SERVICE REQUEST is an EXTENDEDSERVICE REQUEST.
 33. The method according to claim 25, furthercomprising: establishing packet data network services with the secondcontext for Internet protocol multimedia subsystem signaling;establishing an emergency session with an Internet Protocol multimediasubsystem; and activating a voice data context for the establishedemergency session.
 34. The method of claim 25, further comprisingsynchronizing current context status information of the user equipmentwith the wireless network.
 35. A system, comprising: circuitryconfigured to unilaterally deactivate a first active context with awireless network while maintaining a second context as active,responsive to a request to establish an emergency service; and atransmitter configured to transmit, to the wireless network, a requestto establish the emergency service, the request identifying theemergency service and the active second context.
 36. The system of claim35, wherein the circuitry is further configured to establishing theemergency service using the wireless network with which the firstcontext was deactivated.
 37. The system of claim 35, wherein thecircuitry is configured to deactivate the first active contextunilaterally.
 38. The system of claim 35, wherein the transmitter isfurther configured to transmit an emergency attach request to thewireless network, responsive to the local deactivation clearingresources used for active packet domain communication.
 39. The system ofclaim 35, wherein the transmitter is further configured to transmit adeactivation message to the wireless network explicitly indicating thefirst context as a deactivated context.
 40. The system of claim 39,wherein the transmitter is further configured to transmit thedeactivation message subsequent to transmission of the request to thewireless network to establish the emergency service.
 41. The system ofclaim 39, wherein the transmitter is further configured to transmit, tothe wireless network, a SERVICE REQUEST, and one of a PDN CONTEXTDEACTIVATION or a PDN DISCONNECT REQUEST including a cause indicatorexplicitly identifying the service as an emergency service.
 42. Thesystem of claim 41, wherein the SERVICE REQUEST is an EXTENDED SERVICEREQUEST.
 43. The system of claim 35, wherein the circuitry is furtherconfigured for: establishing packet data network services with thesecond context for Internet protocol multimedia subsystem signaling;establishing an emergency session with an Internet Protocol multimediasubsystem; and activating a voice data context for the establishedemergency session.
 44. A non-transitory computer-readable storage mediumcomprising a set of computer-readable instructions stored thereon,which, when executed by a processing system, cause the processing systemto perform the steps of: deactivating a first active context with awireless network, by a user equipment, while maintaining a secondcontext as active, responsive to a request to establish an emergencyservice; and transmitting a request to establish the emergency serviceto the wireless network, by the user equipment, the request identifyingthe emergency service and the active second context.